4-67
The phase of a vibration modulated signal is
When the oscillator is subjected to a
sinusoidal vibration, the peak
phase excursion is
Example:
if a 10 MHz, 1 x 10-9/g oscillator is subjected to a 10
Hz
sinusoidal vibration of amplitude 1g,
the peak vibration-induced phase
excursion is 1 x 10-3 radian. If this oscillator is used as the
reference
oscillator in a 10 GHz radar system,
the peak phase excursion at 10GHz
will be 1 radian. Such a large phase excursion can be
catastrophic to
the performance of many systems, such
as those which employ phase
locked loops (PLL) or phase shift
keying (PSK).
Vibration-Induced Phase Excursion